Mixed messages from ministers are undermining the attempts of schools to raise educational standards, a former adviser to Tony Blair said.
The Government is encour-aging schools to collaborate at the same time as they compete for pupils, said Mr Blair's former private secretary, Robert Hill.
A former special adviser in the Department for Education, Mr Hill sets out his thoughts in a new book to be published next week by the Association of School and College Leaders.
Mr Hill completed his work on the book, Leadership That Lasts, before the Education Bill was published.
He wrote: "The Government's mixed messages on competition and collaboration between schools are undermining attempts to deliver sustainable improvement at a local level."
Mr Hill continued: "Given that they are competing for parents and pupils and they will be judged by their results, it is hard to see what the drivers for collaboration will be. The risk is that at best pragmatic fixes will emerge and at worst collaboration will be token and ineffective."
A spokesman for the Department for Education and Skills dismissed Mr Hill's comments, which were reported in the current edition of the Times Educational
Supplement. "We do not see a conflict between encouraging individual schools to be the best they can be while working with each other on shared interests," the spokesman said.
These shared interests included managing pupils' behaviour and pooling schools' specialist resources "for the benefit of all their pupils".
"Specialist schools, which make up 80 per cent of all secondary schools, have been doing this successfully for some time," he said.
"At the heart of the Education and Inspections Bill are proposals to drive up standards in every school, particularly those in deprived areas.
"For those schools wishing to collaborate, we believe that trusts will make it easier for them to do so."
There were signs last week that the Labour rebellion on the schools Bill was softening.
Critics said MPs should back the Bill at its second reading on Wednesday and seek further changes during the later stages of the parliamentary process.
Mr Blair has also acknowledged that - given the Conservatives have declared their support for the Bill - he "probably" has no real chance of losing.
A source at the Department for Education and Skills said: "Some people are predicting that Wednesday's vote is on a knife-edge. But the Government's commitment to reform and deliver higher standards is not."